Optical communication components, such as optical fibre transmitters and/or receivers, generally referred to hereinafter as optical transceivers, often need to be connected to other such components or optical fibre transmission cables. For example, an optical transceiver may have a connector port into which connector patch cord is plugged.
One common type of optical fibre connector, disclosed in U.S. Pat. No. 5,315,680, has an optical port inside of which is a hollow cylindrical split sleeve. The split sleeve is ceramic and has a longitudinal slot and is inwardly sprung so that this clamps over a ceramic ferrule within the port. The ferrule is cylindrical and normally has a diameter of 1.25 mm. An optical fibre is mounted concentrically within the ferrule to form a ferrule fibre assembly. The optical fibre may be a fibre stub that is optically connected to one or more other passive of active optical components, for example a solid state laser or detector device as part of an optical transceiver unit. The split sleeve extends forwards of the ferrule, and forms with a surrounding body a connector receptacle into which a connector plug can be inserted.
The connector plug has a cylindrical ceramic ferrule with a concentrically mounted optical fibre. This ferrule is manufactured to the same dimensions and tolerances as the ferrule/fibre assembly within the connector receptacle. The connector plug includes a body portion, with a forwards part of the ferrule/fibre assembly projecting freely from this body portion so that when the connector plug mates with the connector receptacle, the projecting portion of the connector plug fibre/ferrule assembly inserts into the forwards extending portion of the split sleeve.
In addition to providing a convenient means for butt-aligning optical fibres, this arrangement provides several advantages. Because both ferrule/fibre assemblies are manufactured to the same tolerance, the fibres are naturally aligned with respect to each other during the connection process to within a sub-micron accuracy. The extending split ferrule and surrounding body portion also provide an effective optical baffle when no connector plug is connected to the connector receptacle by aperturing stray optical radiation. Furthermore, because the output end of the fibre is recessed within the connector receptacle, the arrangement protects the output end of the fibre from mechanical damage as well as preventing a user's eye from coming closer than a minimum safety from the output end of the fibre. The latter issue is of particular concern as the wavelength of the optical radiation is normally either 1.31 μm or 1.55 μm, and is therefore invisible to the human eye.
Although the arrangement described above works effectively, there is a significant amount of cost in manufacturing the various components of the connector receptacle, particularly the ferrule/fibre assembly, which must be formed with an outer diameter toleranced to ±0.5 μm, so that the fibres are axially aligned to within ±1 μm.